CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Income Statement [Abstract]
Sales	$ 323,351	$ 268,694	$ 619,910	$ 525,514
Cost of sales	204,064	168,736	392,912	329,882
Gross profit	119,287	99,958	226,998	195,632
Selling, general, and administrative expenses	93,637	77,976	178,362	153,014
Restructuring charges	838	2,150	1,364	2,150
Operating profit	24,812	19,832	47,272	40,468
Pension settlement charge	4,608	0	4,608	0
Interest expense	5,252	1,859	10,780	3,530
Other income, net	(2,792)	(2,169)	(6,794)	(4,360)
Income before income tax expense	17,744	20,142	38,678	41,298
Income tax expense	4,621	7,182	10,288	12,946
Net earnings	13,123	12,960	28,390	28,352
Net (loss) earnings attributable to noncontrolling interests	(1)	22	7	14
Net earnings	$ 13,124	$ 12,938	$ 28,383	$ 28,338
Net earnings per common share attributable to Knoll, Inc. stockholders:
Basic (in dollars per share)	$ 0.27	$ 0.27	$ 0.58	$ 0.59
Diluted (in dollars per share)	0.27	0.26	0.58	0.57
Dividends per share (in dollars per share)	$ 0.15	$ 0.15	$ 0.30	$ 0.3
Weighted-average number of common shares outstanding:
Basic (in shares)	48,672,144	48,464,605	48,614,733	48,375,241
Diluted (in shares)	49,131,106	49,376,506	49,137,528	49,294,525
Other comprehensive (loss) income:
Unrealized gain on interest rate swap, net of tax	$ 1,183	$ 0	$ 1,053	$ 0
Pension and other post-employment liability adjustment, net of tax	7,669	(138)	7,880	(275)
Foreign currency translation adjustment	(5,961)	2,320	(6,300)	2,800
Foreign currency translation adjustment on long term intercompany notes	(5,085)	0	(5,592)	0
Total other comprehensive (loss) income, net of tax	(2,194)	2,182	(2,959)	2,525
Total comprehensive income	10,929	15,142	25,431	30,877
Comprehensive (loss) income attributable to noncontrolling interests	(1)	22	7	14
Comprehensive income attributable to Knoll, Inc. stockholders	$ 10,930	$ 15,120	$ 25,424	$ 30,863